DE69917160T2 - Tubeless tire - Google Patents

Description

The The present invention relates to a pneumatic tire in which the Innerliner is dispensed with in order to reduce the tire weight, and the steering stability, driving comfort, durability and the like can be improved can.

at Pneumatic tires that are used without a tube are the inside of the tire covered with an inner liner made of an air-impermeable butyl rubber mixture is made, which is arranged on the inside of the carcass is.

EP-A-0 705 717 discloses a pneumatic tire according to the preamble of claim 1. Japanese Patent Application Laid-Open Nos. JP-A-6-156007 and JP-A-8-113007 ( EP 0 705 717 ) disclose tubeless tires to reduce the tire weight, in which a butyl rubber mixture is used for the rubber coating of the carcass and the inner liner is eliminated.

however butyl rubber has low impact resilience in comparison with diene rubber, which is usually is used as a rubber coating, and so with butyl rubber as carcass rubber the steering stability, driving comfort and the like bad.

If, like it used to be was suggested about it In addition, butyl rubber can be used as carcass rubber easily a detachment failure occur at the end of the carcass ply when there is a concentration of tension occurs.

It is also known from US-A-5 711 829, at least one layer Monofilament cords for the belt to be used, which are laid at least at an angle of 10 ° to 14 °, around a belt package with improved stamina against belt layer detachment.

It is therefore an object of the present invention, a tubeless To provide tires in which a butyl rubber compound as Carcass rubber is used, but also the steering stability and the Driving comfort are good.

It is another object of the present invention, a tubeless To provide tires in which a butyl rubber compound as Carcass rubber is used in which such a separation failure is prevented, which improves durability.

Accordingly the present invention provides a pneumatic tire according to claim 1 ready. Further aspects of the invention are specified in the subclaims.

embodiments The present invention will now be read in conjunction with the accompanying drawings described in detail.

1 Fig. 4 is a sectional view of an embodiment of the present invention;

2 (A) - (B) are sectional views of a monofilament cord and a multifilament cord;

3 (A) - 3 (C) are schematic sectional views for explaining the thickness of the carcass ply rubber;

4 Fig. 12 is a partial sectional view of a part of the carcass with a turn portion and a main portion of the carcass ply adjacent to each other;

5 Figure 3 is a sectional view of another embodiment of the present invention that includes an additional cord layer;

6 Fig. 12 is a sectional view showing a modification of its additional cord layer;

7 Figure 4 is a sectional view of yet another embodiment of the present invention that includes an additional cord layer;

8 (A) - 8 (B) are partial sectional views of the carcass; and

9 is a sectional view of a prior art tire.

In the drawings, includes a pneumatic tire 1 a tread portion according to the present invention 2 , a pair of side wall sections 3 , a pair of axially spaced bead portions 4 each with a bead core 5 in a carcass 6 that are between the bead sections 4 through the tread section 2 and the side wall sections 3 stretches a belt 7 that is radially outside the carcass 6 in the tread section 2 is arranged, and a bead apex 8th which is made of hard rubber and in each of the bead portions 4 is arranged.

at this invention is not a conventional one Inner liner, which is arranged along the inside of the carcass, intended.

All Tires illustrated are radial tires for passenger cars.

If nothing specifically mentioned is the different sizes and Dimensions in normal filling condition of the tire measured by mounting the tire on a standard rim and inflated to a standard pressure, but not with a tire load is burdened. Here the standard rim is the "standard rim" specified in JATMA is the "Measuring Rim " in ETRTO, the "Design Rim "(construction rim) in TRA or the like. The standard pressure is the "maximum air pressure" in JATMA, the "Inflation Pressure " in ETRTO, the maximum pressure specified in the table "Tire Load Limits at Various Cold Inflation Pressures "(tire load limits at various Inflation pressures in cold state) is specified in TRA, or the like. The standard load is the "maximum load capacity " in JATMA, the "Load Capacity " in ETRTO, the maximum value specified in TRA in the above table is, or the like. The bead base line BL mentioned below is an axial line at a radial height that corresponds to the rim diameter corresponds to the standard rim.

The carcass mentioned above 6 includes at least one layer 6A from cords 10A , which are arranged radially at an angle of 75 to 90 degrees with respect to the tire equator C and between the bead portions 4 through the tread section 2 and the side wall section 3 extend and around the bead core 5 in each bead section 4 are turned over from the axial inside to the outside of the tire by a pair of cover portions 6b and a main section 6a to form in between.

For the carcass cords 10A organic fiber cords, e.g. As polyester, nylon, rayon, aromatic polyamide, vinylon or the like used.

The innermost carcass ply, which in the illustrated examples is the ply mentioned above 6A is through an inner rubber layer 11i and an outer rubber layer 11o rubberized.

The inner rubber layer 11i is on one side of the innermost carcass ply 6A arranged so that it is the tire's air cavity between one of the bead portions 4 and facing the other, and the outer rubber layer 11o is on the other side of the innermost carcass ply 6A arranged.

The inner rubber layer 11i is made from a butyl rubber mixture containing at least 10 parts by weight, preferably at least 30 parts by weight of butyl rubber or a butyl rubber derivative with respect to 100 parts by weight of a base rubber. Here, butyl rubber means a copolymer (IIR) of isobutylene and a small amount of isoprene. The butyl rubber derivative is halogenated butyl rubber such as chlorinated butyl rubber and brominated butyl rubber. Usually, the butyl rubber compound further contains reinforcing agents such as carbon black, vulcanizing agent, vulcanization accelerator, plasticizer and the like. In addition, the butyl rubber mixture may contain diene rubber such as natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR) and the like as its base rubber.

The outer rubber layer 11o is made from a non-butyl rubber blend containing at least 90 parts by weight, preferably 100 parts by weight of diene rubber with respect to 100 parts by weight of a base rubber.

The The following Table 1 shows an example A of the butyl rubber mixture and Example B of the non-butyl rubber blend.

Table 1 (parts by weight)

In order to obtain a sufficient air sealing effect, the minimum thickness is Ti of the inner rubber coating 11o , measured from its inner surface to the carcass cords 10A , in the range of 0.2 to 1.0 mm, preferably 0.3 to 0.8 mm. If the minimum thickness Ti is less than 0.2 mm, the necessary airtightness cannot be obtained. If the minimum thickness Ti is larger than 1.0 mm, there is a deterioration in steering stability and driving comfort, and the tire weight increases.

The boundary E between the inner rubber layer 11i and the outer rubber layer 11o can be arranged on a center line N, which is the center of the cords 10A connects as it is in 3 (A) is shown, or outside the centerline N, as in 3 (B) is shown, or within the centerline N as shown in 3 (C) is shown. From the viewpoint of the balance between the steering stability and the driving comfort and the adherence to the carcass cords, however, the maximum rubber thickness T of the inner rubber layer, measured from its surface to the boundary E, is preferably not larger than Ti + 0.5 D and not larger than 1.5 mm. For example, the thickness T is 0.5 to 1.0 mm.

Around the tread section mentioned above 2 , the sidewall sections 3 and the bead sections 4 to be defined are a tread rubber 2G , a sidewall rubber 3G and a bead rubber (abrasion strip rubber) 4G outside the carcass 6 arranged. Conventional rubber compounds other than the butyl rubber compound mentioned above can be used for these materials.

The belt mentioned above includes a breaker 7 and optionally a band or bandage wrapped around it.

The breaker 7 comprises at least one layer of monofilament cords 20 and optionally a layer of multifilament cords 30 , where each layer extends over at least 80% of the tread width.

The monofilament cord 20 is made of a single steel filament, as in 2 (A) is shown. The multifilament cord 30 is made of at least three steel filaments 31 formed that are twisted together as in 2 B) is shown. These filaments 20 and 31 can also be made of organic materials, e.g. B. nylon, rayon, polyester, aramid or the like.

Usually the breaker includes 7 two crossed layers of parallel cords laid at an angle of 10 to 40 degrees with respect to the circumferential direction of the tire, and at least one of the two crossed layers is the above-mentioned monofilament cord layer.

The diameter D1 of the monofilament cord 20 is preferably in the range from 0.35 to 0.55 mm.

The multifilament cord 30 comprises three steel filaments 31 which each have a diameter D2 in the range from 0.20 to 0.40 mm. The diameter D3 of the multifilament cord 30 is in the range of 0.50 to 0.70 mm.

The cross-sectional area 20S of the monofilament cord 20 is in the range of 0.68 to 0.88 times the total cross-sectional area 31S of steel filaments 31 of the multifilament cord 30 established.

For example, if the multifilament cord 30 has a 1 × 3 / 0.27 structure (total cross-sectional area = 0.1717 mm ² ) is the cross-sectional area 20S of the monofilament cord 20 in the range from 0.117 to 0.151 mm ² : Thus the diameter D 1 of the monofilament cord 20 is in the range from 0.39 to 0.44 mm (in this example 0.42 mm for 1 × 3 / 0.27).

The Cord titer N of the monofilament cord layer and the multifilament cord layer is in the range of 33 to 47 (cords / 5 cm).

The Band (not shown) is located radially outside of the breaker and consists of spiral windings of at least one cord or one Strip containing parallel cords. The cord angle is smaller than 10 degrees, usually essentially 0 degrees with respect to the circumferential direction of the tire.

The explained above Construction can not only on passenger car tires but also on motorcycle tires, van tires and the like can be applied.

table 2 shows results of comparative tests in which all test tires except for their belt structure, their carcass ply rubber and their inner liner the same Had structure.

Airtightness test

The Tire mounted on a standard rim and under normal pressure was pumped up for 15 days in a hot Chamber at 80 ° C posed. Then the pressure drop was measured and its reciprocal through specified an index based on the fact that the tire from the Prior art has an index of 100. The bigger the Index, the better the airtightness.

Production efficiency test

It was measured the time it took to get the green tire manufacture. The results are indicated by an index, the is based on the fact that the tire from the prior art has an index of 100. The smaller the index, the better it is Production efficiency.

Steering stability and driving comfort test

On Test car running on all four wheels was equipped with test tires, was driven on a test track, and the steering stability (Steering response, rigidity, grip, transient cornering force, linearity, critical cornering speed) were caused by the driver's feeling rated based on ten ranks. The higher the rank is the higher is the steering stability. Furthermore, the test car was on a bumpy track, one with stone cobbled street and a gravel road driven on a tire test track and the driving comfort (roughness, Postponing, steaming) was by feeling of the driver in ten ranks. The higher the rank is, the better the driving comfort.

tire weight

Anmerkung: Gürtelkordwinkel sind plus/minus 24 Grad in Bezug auf den Reifenäquator
Reifengröße: 195/65R14, Felgengröße: 6JJX14 (Standardfelge), Reifendruck: 200 kPa (normal)
Testwagen: Personenwagen mit Frontantrieb und 2000 cm³ The weight of the tire was measured and indicated by an index based on the prior art tire having an index of 100. The smaller the index, the lower the weight. Table 2

Note: Belt cord angles are plus / minus 24 degrees with respect to the tire equator
Tire size: 195 / 65R14, rim size: 6JJX14 (standard rim), tire pressure: 200 kPa (normal)
Test car: Passenger car with front-wheel drive and 2000 cm ³

On based on the above Basic structure can various modifications can be made as follows:

* Thin bead apex

In order to further reduce the tire weight, it is possible to reduce the volume of the apex mentioned above 8th decrease as it is in 1 is shown. This structure can be applied not only to passenger car tires, but also to motorcycle tires, van tires and the like. In this case it is effective to remarkably decrease the bead apex height Ha compared to the ordinary height so that the height Ha is roughly the same as that of the horn Jf of the standard wheel rim J for the tire. The height Ha is then in the range of 10 to 20 mm, preferably 13 to 17 mm from the bead base line BL.

The bead apex 8th is made of relatively hard rubber with a JIS-A hardness of 65 to 95 degrees, preferably 70 to 90 degrees, and tapers radially outward from the bead core.

Furthermore, the height Ht of the carcass ply handling section 6b be greater than the height Ha of the bead apex 8th to an adjacent part 15 form, in which the carcass ply handling section 6b and the main section 6a are adjacent to each other. This structure helps to improve steering stability and driving comfort.

The height Hb of the radially outer end 6e of the envelope section 6b is set in the range of 0.3 to 0.7 times, preferably 0.40 to 0.55 times, the tire cross-sectional height H, in each case from the bead base line BL.

Near the outer end 8e the bead apex 8th is the envelope section 6b is concavely curved along the axially outer side of the bead apex, and the radius R of the curvature is in the range of 5 to 15 mm, preferably 8 to 12 mm, whereby separation due to residual air can be prevented.

In the neighboring part 15 the rubber thickness Tb lies between the cords in the cover section 6b and the adjacent cords in the main section 6a in the range of 0.3 to 0.8 mm as in 4 is shown.

If the thickness Tb is less than 0.3 mm, a sheet peeling error can easily occur occur. If the thickness Tb is greater than Is 0.8 mm, the tire weight is increased.

If the apex height Ha is less than 10 mm, it is difficult to manufacture such a structure. When the apex height Ha is larger than 20 mm, the tension in the turnup portion decreases 6b too, and detachment from there can easily occur.

If the height Ht is less than 0.3 times the height H, the transverse stiffness insufficient and the steering stability deteriorates greatly. If the height Ht greater than 0.7 times the height H is, the driving comfort is reduced.

Reifengröße: 175/70R13, Felgengröße: 5JJX13 (Standardfelge)
Testwagen: Personenwagen mit Frontantrieb und 1600 cm³ Table 3 shows results of comparative tests, test tires having the same structure with the exception of the bead apex, the carcass ply rubber and the inner liner. Table 3

Tire size: 175 / 70R13, rim size: 5JJX13 (standard rim)
Test car: Passenger car with front-wheel drive and 1600 cm ³

Additional cord layer in the upper side wall

The 5 and 6 show further modifications in which the carcass 6 from a single location 6A is formed, an additional cord layer 13 outside the carcass 6 is arranged and the height of the carcass ply handling sections 6b is reduced, but the height of the apex 8th is increased again. This structure can be applied to motorcycle tires, light commercial vehicle tires or the like in addition to passenger car tires.

The bead apex 8th is made of hard rubber with a JIS-A hardness of 65 to 95 degrees, preferably 70 to 90 degrees.

The height Ha of the radially outer end 8e the bead apex 8th is 0.15 to 0.55 times, preferably 0.15 to 0.30 times the tire cross-sectional height H.

The radially outer end 6e of the envelope section 6b is radially inner with respect to the radially outer end 8e the bead apex 8th arranged, and the radial distance h between the ends 6e and 8e is at least 5 mm, preferably not less than 10 mm, and is more preferably in the range of 10 to 25 mm.

The bead apex rubber 8th is relatively hard and relatively thick in the lower part. Therefore, its bending deformation is relatively small. Thus, by arranging the cover end 6e next to the bead apex 8th a breakdown failure can be prevented and the durability is improved.

The additional cord layer 13 is formed from a single layer of radially arranged cords and both sides are rubberized with the above-mentioned non-butyl rubber compound.

The additional cord layer 13 has a radially inner end 13e in each of the side wall sections 3 on. The radially inner end 13e is located at a location radially outward from the radially outer end 8e of the bead apex, and the radial distance S between them is in the range of 10 to 15 mm. The additional cord layer 13 extends at least from each of the radially inner ends 13e to a point below the belt 7 , If not, the steering stability deteriorates. When the carcass cord angle 90 Degrees with respect to the tire equator, the cord angle of the additional cord layer is also set to 90 degrees. If the carcass cord angle is not 90 degrees, the cords of the additional cord layer are arranged at an angle equal to or similar to that of the carcass cord angle so that it crosses the carcass cords. The additional cord layer 13 is preferably capable of being the same as the carcass ply in terms of the material, size and structure of the cord and cord titer.

5 shows an example of an additional cord layer 13 that extend continuously from one of the side wall sections 3 extends to the other. In this case, the steering stability is further improved.

6 shows another example of the additional cord layer 13 that under the belt 7 is interrupted, so it is made of two axially spaced parts 13B manufactured. In this case, the tire weight is further reduced.

Anmerkung: radial "außen" oder "innen" des radial äußeren Endes des Wulstkernreiters
Reifengröße: 195/65R14. Felgengröße: 6JJX14 (Standardfelge)
Innendruck: 200 kPa (normal), Testwagen: Personenwagen mit Vorderradantrieb und 2000 cm³ 4 shows results of comparative tests, with test tires having the same structure with the exception of the bead apex, the carcass ply rubber and the inner liner. Table 4

Note: radially "outside" or "inside" the radially outer end of the apex
Tire size: 195 / 65R14. Rim size: 6JJX14 (standard rim)
Internal pressure: 200 kPa (normal), test car: passenger car with front wheel drive and 2000 cm ³

additional Cord layer in the lower side wall

7 shows another modification in which the carcass 6 from a single location 6A is formed and a bead reinforcing cord layer 9 between the carcass ply handling section 6b and the bead apex 8th is arranged. This structure can be applied to motorcycle tires, light truck tires and the like in addition to passenger car tires.

The bead apex 8th has a JIS-A hardness of 65 to 95 degrees, more preferably 70 to 90 degrees.

The bead reinforcement cord layer 9 is made of cords laid at an angle of 10 to 60 degrees (10 to 30 degrees in this example) with respect to the circumferential direction of the tire and both sides of which are rubberized with the above-mentioned non-butyl rubber. Steel cords and organic high modulus cords such as aromatic polyamide and the like are preferably used for such cords.

The radially inner end 9d the bead reinforcing cord layer 9 is preferably at a distance L of not more than 7 mm from the radial outside of the bead core 5 arranged.

The height Hs of the bead reinforcing cord layer 9 is larger than the height Ha of the bead apex 8th but less than the height Ht of the carcass ply section 6b , The size Ha is set in the range of 0.20 to 0.40 times the tire cross-sectional height H. The height Hs is set in the range of 0.30 to 0.50 times the tire cross-sectional height H. The height Ht is set in the range of 0.40 to 0.60 times the tire cross-sectional height H, and the difference (Hs-Ha) is preferably not less than 10 mm and the difference (Ht-Hs) is not less than 5 mm. If not, the durability can easily become poor due to stress concentration. It is particularly preferred that the difference (Hs-Ha) and the difference (Ht-Hs) have substantially the same value of 0.1 to 0.15 times the tire cross-sectional height H. Here, each height is measured radially from the bead base line BL.

Like it in 8 (A) is in a first area Y1 between the outer ends 8e and 9e the bead apex 8th or the bead reinforcing cord layer 9 the rubber thickness T1 between the cords in the bead reinforcing cord layer 9 and the neighboring carcass cords 10A in the envelope section 6b set in the range of 0.2 to 0.5 mm.

Like it in 8 (B) is in a second area Y2 between the outer ends 9e and 6e the bead reinforcing cord layer 9 or the carcass ply section 6b the rubber thickness T2 between the carcass cords 10A in the envelope section 6b and the carcass cords 10A in the main carcass section 6a set in the range of 0.3 to 0.8 mm.

Reifengröße: 195/65R14, Radfelgengröße 6JJX14 (Standardfelge)
Innendruck: 200 kPa (normal), Testwagen: Personenwagen mit Vorderradantrieb und 2000 cm³ Table 5 shows results of comparative tests in which test tires all had the same structure except for the bead reinforcing cord layer, the carcass ply rubber and the inner liner. Table 5

Tire size: 195 / 65R14, wheel rim size 6JJX14 (standard rim)
Internal pressure: 200 kPa (normal), test car: passenger car with front wheel drive and 2000 cm ³

How as described above is the tubeless tire according to the present Invention for removing a conventional inner liner the rubber layer on one side of the innermost carcass ply made of a butyl rubber mixture manufactured with a specific thickness, and at least one of the belt plies is made of monofilament cords. As a result, the steering stability, the driving comfort and the like improved. Furthermore, by applying the small Bead apex and by providing the one adjacent to the carcass ply Partly the tire weight can be further reduced and a reduction durability due to carcass ply detachment can be prevented.

Claims (10)

A pneumatic tire comprising a tread portion ( 2 ), a pair of side wall sections ( 3 ), a pair of bead sections ( 4 ), each with a bead core ( 5 ) in a carcass ply ( 6A ) that are located between the bead sections ( 4 ) extends and a rubber layer ( 11i ) facing the inside of the tire and made from a butyl rubber mixture containing at least 10 parts by weight of butyl rubber or butyl rubber derivative, and a belt ( 7 ), the radial outside of the carcass in the tread fen section ( 2 ) is arranged, the thickness (Ti) of the butyl rubber mixture, measured between the inner surface of the tire and adjacent cords of the carcass ply ( 6A ) is in the range of 0.2 to 1.0 mm, characterized in that the belt ( 7 ) at least one layer of monofilament cords ( 20 ), which are set at an angle of 10 to 40 degrees with respect to the circumferential direction of the tire, the monofilament cord ( 20 ) consists of a single filament and an additional layer of cord ( 13 ) which is gummed with a non-butyl rubber compound and outside the carcass ply ( 6A ) is arranged, the additional cord layer ( 13 ) a radially inner end ( 13e ) in each side wall section ( 3 ), the radially inner end ( 13e ) from the radially outer end ( 8e ) the bead apex ( 8th ) is arranged radially outside at a distance (S) of 10 to 15 mm, and the additional cord layer ( 13 ) from each radially inner end ( 8e ) at least up to a position below the belt ( 7 ) extends radially outwards. A pneumatic tire according to claim 1, characterized by two layers of monofilament cords ( 20 ). A pneumatic tire according to claim 1 or 2, characterized in that the belt ( 7 ) a location ( 7B ) made of multifilament cords ( 30 ) which are placed at an angle of 10 to 40 degrees with respect to the circumferential direction of the tire. A pneumatic tire according to claim 1, 2 or 3, characterized in that the carcass ply ( 6A ) around the bead core ( 5 ) in each bead section ( 4 ) is folded around a pair of envelope sections ( 6b ) and a main section ( 6a ) in between, with each bead portion ( 4 ) between the envelope section ( 6b ) and the main section ( 6a ) with a bead apex ( 8th ) is provided, the bead apex ( 8th ) from the bead core ( 5 ) extends radially outwards, and the height (Ha) of its radially outer end ( 8e ) is from 10 to 20 mm from a bead base line (BL), the cover section ( 6b ) radially outwards over the radially outer end ( 8e ) the bead apex ( 8th ) extends so that it connects to the main section ( 6a ) and the thickness (Tb) of the rubber between the cords in the cover portion ( 6b ) and the cords in the main section ( 6a ) Is 0.3 to 0.8 mm. A pneumatic tire according to claim 4, characterized in that the height (Ha) of the radially outer end ( 8e ) the bead apex ( 8th ) is 0.15 to 0.55 times the tire cross-sectional height (H), and the radial distance between the radially outer end ( 8a ) the bead apex ( 8e ) and the end of the envelope section ( 6b ) is not less than 5 mm. A pneumatic tire according to one of claims 1 to 5, characterized in that the additional cord layer ( 13 ) continuously between its radially inner ends ( 13e ) extends. Pneumatic tire according to one of claims 1 to 5, characterized in that the additional cord layer ( 13 ) in the tread section below the belt ( 7 ) is interrupted. A pneumatic tire according to claim 1, 2 or 3, characterized in that the carcass ply ( 6A ) around the bead core ( 5 ) in each bead section ( 4 ) is folded around a pair of envelope sections ( 6b ) and a main section ( 6a ) in between, with each bead portion ( 4 ) between the envelope section ( 6b ) and the main section ( 6a ) with a bead apex ( 8th ) which extends from the bead core ( 5 ) extending radially outward, a bead reinforcing cord layer ( 9 ) between the bead apex ( 8th ) and the envelope section ( 6b ) in each bead section ( 4 ) is arranged, the height (Hs) of the radially outer end ( 9e ) the bead reinforcing cord layer ( 9 ) is greater than the height (Ha) of the radially outer end ( 8e ) the bead apex ( 8th ), but less than the height (Ht) of the radially outer end ( 6e ) of the envelope section ( 6b ), in a first area (Y1) between the end ( 8e ) and the end ( 9e ) the thickness (T1) of the rubber between the cords in the cover section ( 6b ) and the cords in the bead reinforcing cord layer ( 9 ) Is 0.2 to 0.5 mm, in a second area (Y2) between the end ( 9e ) and the end ( 6e ) the thickness (T2) of the rubber between the cords in the main section ( 6a ) and the cords in the cover section ( 6b ) Is 0.3 to 0.8 mm. A pneumatic tire according to claim 8, characterized in that the height (Ht) of the cover portion is 0.4 to 0.60 times the tire cross-sectional height, the height (Hs) of the bead reinforcing cord layer being 0.3 to 0.50 times the tire cross-sectional height the height (Ha) of the apex ( 8th ) is 0.20 to 0.40 times the tire section height, the difference (Hs-Ha) between the height (Ha) and the height (Hs) is not less than 10 mm, and the difference (Ht-Hs) between the height (Hs) and the height (Ht) is not less than 0.5 mm. A pneumatic tire according to claim 8, characterized in that the difference (Hs-Ha) and the difference (Ht-Hs) are essentially same values of 0.1 to 0.15 times the tire cross-sectional height (H).